TV tuner and the manufacturing method thereof

ABSTRACT

A TV tuner includes an Ultra High Frequency (UHF)/Very High Frequency (VHF) tracking filter, an UHF/VHF matching circuit and a single conversion Tuner IC. The UHF/VHF tracking filter includes a first Low-Temperature Co-fired Ceramics (LTCC) inductor, a first varactor diode and a fine-tune capacitor electrically connected to determine the maximum gain frequency of the UHF/VHF tracking filter. The UHF/VHF matching circuit includes a second LTCC inductance, a second varactor diodes and a fine-tune capacitor electrically connected to determine the maximum gain frequency of the UHF/VHF matching circuit.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number95133753, filed Sep. 12, 2006, which is herein incorporated byreference.

BACKGROUND

1. Field of Invention

The present invention relates to a TV tuner and a manufacturing methodthereof. More particularly, the present invention relates to an ultrahigh frequency/very high frequency TV tuner.

2. Description of Related Art

A TV tuner plays an important role in the digital TV, a Set Top Box anda portable transmitting/receiving communication system. The TV tuner isused to amplify the received radio frequency (RF) signal, select thedesired signal and filter out the undesired signal to prevent undesiredsignals affecting the desired ones. After that, the TV tuner lowers thefiltered RF signal to an Intermediate Frequency signal.

Because the digital TV needs to be portable, the demands for smalldigital TVs has increased. However, the air coils used in the TV tunerrequire a lot of space and need to be plugged in by human hands, whichincreases the cost and makes portability difficult.

For the forgoing reasons, there is a need for a new TV tuner for asmall, portable digital TV.

SUMMARY

According to one embodiment of the present invention, a TV tuner havingan Ultra High Frequency (UHF) tracking filter, a UHF matching circuitand a single conversion Tuner IC, characterized in that the UHF trackingfilter includes at least one first Low-Temperature Co-fired Ceramics(LTCC) inductor, a first varactor diode and a fine-tune capacitorelectrically connected to determine the maximum gain frequency of theUHF tracking filter; the UHF matching circuit includes at least onesecond LTCC inductor, a second varactor diode and a capacitorelectrically connected to determine the maximum gain frequency of theUHF matching circuit.

According to another embodiment of the present invention, a TV tunerhaving a Very High Frequency (VHF) tracking filter, a VHF matchingcircuit and a single conversion Tuner IC, characterized in that the VHFtracking filter includes at least one first LTCC inductor, a firstvaractor diode and a fine-tune capacitor electrically connected todetermine the maximum gain frequency of the VHF tracking filter; the VHFmatching circuit includes at least one second LTCC inductor, a secondvaractor diode and a capacitor electrically connected to determine themaximum gain frequency of the VHF matching circuit.

According to another embodiment of the present invention, a method formanufacturing a TV tuner which has a UHF tracking filter, a UHF matchingcircuit and a single conversion Tuner IC, characterized in that usingLTCC inductors in the UHF tracking filter and the UHF matching circuitto determine the maximum gain frequency; tuning the single conversionTuner IC for a tuned-voltage, in which the tuned-voltage determines thecapacitances of a first varactor diode and a second varactor diode ofthe UHF tracking filter and the UHF matching circuit respectively; andtuning the capacitance of a fine-tune capacitor of the UHF trackingfilter and the inductance of the LTCC inductor of the UHF matchingcircuit to determine the maximum gain frequency of the UHF trackingfilter and the UHF matching circuit.

According to another embodiment of the present invention, a method formanufacturing a TV tuner which has a Very High Frequency (VHF) trackingfilter, a VHF matching circuit and a single conversion Tuner IC,characterized in that using LTCC inductors in the VHF tracking filterand the VHF matching circuit to determine the maximum gain frequency;tuning the single conversion Tuner IC for a tuned-voltage, wherein thetuned-voltage determines the capacitances of a first varactor diode anda second varactor diode of the VHF tracking filter and VHF matchingcircuit respectively; and tuning the capacitance of a fine-tunecapacitor of the VHF tracking filter and the inductance of the LTCCinductor of the VHF matching circuit to determine the maximum gainfrequency of the VHF tracking filter and the VHF matching circuit.

It is to be understood that both the foregoing general description andthe following detailed description are by examples, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is a TV tuner according to one embodiment of the presentinvention;

FIG. 2A is an Ultra High Frequency (UHF) tracking filter according toone embodiment of present invention;

FIG. 2B is the frequency response of the UHF tracking filter accordingto one embodiment of present invention;

FIG. 3A is a UHF matching circuit according to one embodiment of presentinvention;

FIG. 3B is the frequency response of the UHF matching circuit accordingto one embodiment of present invention;

FIG. 4A is a Very High Frequency (VHF) tracking filter according to oneembodiment of present invention;

FIG. 4B is the frequency response of the VHF tracking filter accordingto one embodiment of present invention;

FIG. 5A is a VHF matching circuit according to one embodiment of presentinvention;

FIG. 5B is the frequency response of the VHF matching circuit accordingto one embodiment of present invention; and

FIG. 6 is a single conversion Tuner IC according to one embodiment ofpresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

FIG. 1 is a TV tuner according to one embodiment of the presentinvention. The TV tuner includes an antenna 101, a pre-amplifier 103, anUltra High Frequency (UHF) tracking filter 105, two second amplifiers107 and 113, a UHF matching circuit 109, a Very High Frequency (VHF)tracking filter 111, a VHF matching circuit 115 and a single conversionTuner IC 117.

The antenna 101 is electrically connected to the pre-amplifier 103, andthe pre-amplifier 103 is electrically connected to the UHF trackingfilter 105 and the VHF tracking filter 111. The UHF tracking filter 105,the second amplifier 107 and the UHF matching circuit 109 areelectrically connected, and the VHF tracking filter 111, the secondamplifiers 113 and the VHF matching circuit 115 are also electricallyconnected. In addition, the UHF matching circuit 109 and the VHFmatching circuit 115 are electrically connected to the single conversionTuner IC 117. The UHF tracking filter 105, the UHF matching circuit 109,the VHF tracking filter 111 and the VHF matching circuit 115 use LTCCinductors instead of air coils.

FIG. 2A is the UHF tracking filter 105 according to one embodiment ofthe present invention. The UHF tracking filter 105 includes a firstvaractor diode 213 a, a fine-tune capacitor 215 a and a first LTCCinductor 209 a. The first end of the first varactor diode 213 a isconnected to the first end of the fine-tune capacitor 215 a, the firstend of the first LTCC inductor 209 a is electrically connected to thesecond end of the fine-tune capacitor 215 a, the second end of the firstLTCC inductor 209 a is electrically connected to the second end of thefirst varactor diode 213 a. In addition, capacitors 201 a, 203 a, 211 aand the LTCC inductors 205 a and 207 a are electrically connected to thefirst varactor diode 213 a and the first LTCC inductor 209 a.

FIG. 2B is the frequency response of the UHF tracking filter 105.Because the capacitances of the first varactor diode 213 a and thefine-tune capacitor 215 a are inversely proportional to the frequencyresponse of the UHF tracking filter 105, such that the maximum gainfrequency of the UHF tracking filter 105 can be tuned by tuning thecapacitance of the first varactor diode 213 a or the fine-tune capacitor215 a. For example, if the capacitances of the first varactor diode 213a and fine-tune capacitor 215 a increase, the frequency response of theUHF tracking filter 105 decreases from the solid line 201 b to thedotted line 203 b. As a result, the maximum gain frequency of the UHFtracking filter 105 decreases from 205 b to 207 b.

FIG. 3A is the UHF matching circuit 109 according to one embodiment ofthe present invention. The UHF matching circuit 109 includes a secondLTCC inductor 305 a, a second varactor diode 313 a and a capacitor 307a. The first end of the second varactor diode 313 a is electricallyconnected to the first end of the capacitor 307 a, the first end of thesecond LTCC inductor 305 a is electrically connected to the second endof the second varactor diode 313 a, and the second end of the secondLTCC inductor 305 a is electrically connected to the second end of thecapacitor 307 a. In addition, capacitors 303 a, 309 a, 311 a andresistor 301 a are electrically connected to the second LTCC inductor305 a, the second varactor diode 313 a and the capacitor 307 a.

FIG. 3B is the frequency response of the UHF matching circuit 109.Because the inductance of the second LTCC inductor 305 a and thecapacitance of the second varactor diode 313 a are inverselyproportional to the frequency response of the UHF matching circuit 109,such that the maximum gain frequency of the UHF matching circuit 109 canbe tuned by tuning the inductance of the second LTCC inductor 305 a orthe capacitance of second varactor diode 313 a. For example, If theinductance of the second LTCC inductor 305 a or the capacitance of thesecond varactor diode 313 a increases, the frequency response of the UHFmatching circuit 109 decreases from the solid line 301 b to the dottedline 303 b. As a result, the maximum gain frequency decreases from 305 bto 307 b.

FIG. 4A is the VHF tracking filter 111. The VHF tracking filter 111includes a first LTCC inductor 405 a, a first varactor diode 413 a and afine-tune capacitor 415 a electrically connected. In addition, there arestill other capacitors 401 a, 411 a and other inductors 403 a, 407 aelectrically connected to the first varactor diode 413 a and the firstLTCC inductor 405 a.

FIG. 4B is the frequency response of the VHF tracking filter 111.Because the capacitances of the fine-tune capacitor 415 a and the firstvaractor diode 413 a are inversely proportional to the frequencyresponse of the VHF tracking filter 111, such that the maximum gainfrequency of the VHF tracking filter 111 can be tuned by tuning thecapacitances of the fine-tune capacitor 415 a and the first varactordiode 413 a.

If the capacitances of the fine-tune capacitor 415 a or the firstvaractor diode 413 a increases, the frequency response of the VHFtracking filter 111 decreases from the solid line 401 b to the dottedline 403 b, such that the maximum gain frequency decreases from 405 b to407 b. On the contrary, if the capacitances of the fine-tune capacitor415 a or the first varactor diode 413 a decreases, the frequencyresponse of the VHF tracking filter 111 increases.

FIG. 5A is the VHF matching circuit 115. The VHF matching circuit 115includes a second LTCC inductor 503 a, a second varactor diode 509 a anda capacitor 507 a. The first end of the second varactor diode 509 a iselectrically connected to the first end of the capacitor 507 a, thefirst end of the second LTCC inductor 503 a is electrically connected tosecond end of the capacitor 507 a. In addition, the capacitor 501 a andLTCC inductor 505 a are electrically connected to the second LTCCinductor 503 a and the capacitor 507 a.

FIG. 5B is the frequency response of the VHF matching circuit 115.Because the inductance of the second LTCC inductor 503 a is proportionalto the frequency response of the VHF matching circuit 115, so themaximum gain frequency can be tuned by tuning the inductance of thesecond LTCC inductor 503 a. If the inductance of the second LTCCinductor 503 a increases, the frequency response moves from the solidline 505 b to the dotted line 507 b, as a result, the maximum gainfrequency increase from the solid line 501 b to the dotted line 503 b.

FIG. 6 is the single conversion Tuner IC 117 according to one embodimentof present invention. The single conversion Tuner IC 117 includes athird varactor diode 615, a third fine-tune capacitor 617, a thirdvariable-capacitor 613, a third LTCC inductor 611 and a third resistor621, in which the third fine-tune capacitor 617 is connected in parallelto the third varactor diode 615. The first end of the thirdvariable-capacitor 613 is electrically connected to the first end of thethird varactor diode 615 and the first end of the third fine-tunecapacitor 617. The first end of the third LTCC inductor 611 iselectrically connected to the second end of the third variable-capacitor613. The second end of the third LTCC inductor 611 is electricallyconnected to the second end of the third varactor diode 615 and thesecond end of the third fine-tune capacitor 617.

The first end of the third resistor 621 is electrically connected to thefirst ends of the third varactor diode 615, the third fine-tunecapacitor 617 and the third variable-capacitor 613, the second end ofthe third resistor 621 is electrically connected to a tuned-voltagegenerating terminal 639. In addition, the capacitors 601, 603, 605, 607and 609 are electrically connected to the third varactor diode 615, thethird fine-tune capacitor 617, the third variable-capacitor 613, thethird LTCC inductor 611 and the resistor 619.

The third variable-capacitor 613 tunes the tuned-voltage such that thetuned-voltage falls within the range of 0 volts to 30 volts, then thethird fine-tune capacitor 617 tunes the tuned-voltage slightly. Thetuned-voltage tunes the capacitances of the first varactor diode 213 aand second varactor diode 313 a of the UHF tracking filter 105 and UHFmatching circuit 109 respectively. If the tuned-voltage increases, thecapacitances of the first varactor diode 213 a and the second varactordiode 313 a decrease.

The single conversion Tuner IC 117 further includes a third varactordiode 629, a third fine-tune capacitor 631, a third variable-capacitor633, a third LTCC inductor 627 and a third resistor 635. The first endof the third LTCC inductor 627 is electrically connected to the firstend of the third variable-capacitor 633. The second end of the thirdLTCC inductor 627 is electrically connected to the second end of thethird varactor diode 629 and the second end of the third fine-tunecapacitor 631.

The second end of the third variable-capacitor 633 is electricallyconnected to the second end of the third varactor diode 629 and thesecond end of the third fine-tune capacitor 631. The first end of thethird resistor 635 is electrically connected to the second end of thethird variable-capacitor 633, the second end of the third resistor 635is electrically connected to a generating terminal of the tuned-voltage639 with very high frequency.

The third variable-capacitor 633 tunes the tuned-voltage such that thetuned-voltage falls within the range of 0 volts to 30 volts, then thethird fine-tune capacitor 631 tunes the tuned-voltage slightly. Thetuned-voltage tunes the capacitances of the first varactor diode 413 aand second varactor diode 509 a of the VHF tracking filter 111 and VHFmatching circuit 115 respectively. If the tuned-voltage increases, thecapacitances of the first varactor diode 413 a and the second varactordiode 509 a decrease.

According to the embodiments, the tracking filters and matching circuitsof the TV tuner use LTCC inductors instead of air coils, which reducesthe volume of the TV tuner such that the digital TV can be portable. Inaddition, the plugging process of the air coils done by human hands canbe omitted, which reduces the cost.

Any element in a claim that does not explicitly state “means for”performing a specified function, or “step for” performing a specificfunction, is not to be interpreted as a “means” or “step” clause asspecified in 35 USC §112, ¶ 6. In particular, the use of “step of” inthe claim herein is not intended to invoke the provisions of 35 USC§112, ¶ 6.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. A TV tuner comprising: a single conversion TunerIC; an Ultra High Frequency (UHF) tracking filter comprising at leastone first Low-Temperature Co-fired Ceramics (LTCC) inductor, a firstvaractor diode and a fine-tune capacitor electrically connected todetermine a maximum gain frequency of the UHF tracking filter; a UHFmatching circuit comprising at least one second LTCC inductor, a secondvaractor diode and a capacitor electrically connected to determine themaximum gain frequency of the UHF matching circuit; a pre-amplifier,electrically connected to inputs of the UHF tracking filter, configuredto amplify input signals; and a second amplifier, electrically connectedbetween the UHF tracking filter and the UHF matching circuit, configuredto amplify output signals of the UHF tracking filter.
 2. A TV tunercomprising: a single conversion Tuner IC; an Ultra High Frequency (UHF)tracking filter comprising at least one first Low-Temperature Co-firedCeramics (LTCC) inductor, a first varactor diode and a fine-tunecapacitor electrically connected to determine a maximum gain frequencyof the UHF tracking filter; and a UHF matching circuit comprising atleast one second LTCC inductor, a second varactor diode and a capacitorelectrically connected to determine the maximum gain frequency of theUHF matching circuit; wherein a first end of the first varactor diode isconnected to a first end of the fine-tune capacitor, a first end of thefirst LTCC inductor is electrically connected to a second end of thefine-tune capacitor, a second end of the first LTCC inductor iselectrically connected to a second end of the first varactor diode. 3.The TV tuner as claimed in claim 1, wherein the capacitances of thefine-tune capacitor and the first varactor diode are inverselyproportional to the determined maximum gain frequency of the UHFtracking filter.
 4. A TV tuner comprising: a single conversion Tuner IC;an Ultra High Frequency (UHF) tracking filter comprising at least onefirst Low-Temperature Co-fired Ceramics (LTCC) inductor, a firstvaractor diode and a fine-tune capacitor electrically connected todetermine a maximum gain frequency of the UHF tracking filter; and a UHFmatching circuit comprising at least one second LTCC inductor, a secondvaractor diode and a capacitor electrically connected to determine themaximum gain frequency of the UHF matching circuit; wherein a first endof the second varactor diode is electrically connected to a first end ofthe capacitor, a first end of the second LTCC inductor is electricallyconnected to a second end of the second varactor diode, and a second endof the second LTCC inductor is electrically connected to a second end ofthe capacitor.
 5. The TV tuner as claimed in claim 1, wherein thecapacitances of the second varactor diode and the inductance of thesecond LTCC inductor are inversely proportional to the determinedmaximum gain frequency of the UHF matching circuit.
 6. The TV tuner asclaimed in claim 1, wherein the single conversion Tuner IC comprises: athird varactor diode; a third fine-tune capacitor, connected in parallelto the third varactor diode; a third variable-capacitor, wherein a firstend of the third variable-capacitor is electrically connected to firstends of the third varactor diode and the third fine-tune capacitor; athird LTCC inductor, wherein a first end of the third LTCC inductor iselectrically connected to a second end of the third variable-capacitor,a second end of the third LTCC inductor is electrically connected to asecond end of the third varactor diode and a second end of the thirdfine-tune capacitor; and a third resistor, wherein a first end of thethird resistor is electrically connected to the first end of the thirdvaractor diode, the first end of the third fine-tune capacitor and thefirst end of the third variable-capacitor, a second end of the thirdresistor is electrically connected to a generating terminal of atuned-voltage with ultra high frequency.
 7. The TV tuner as claimed inclaim 6, wherein the magnitude of the tuned-voltage with ultra highfrequency is inversely proportional to the capacitances of the firstvaractor diode and the second varactor diode.